Drum Water Level Control Based on Improved ADRC

Round 1

Reviewer 1 Report

General and minor comments:

1.      Abstract should overview obtained results and Author’s claims. 2.      The English needs minor improvement. 3.      How is the present paper different from these previous results? The contribution and motivation of the paper needs to be clearly stated. The extended state observer-based feedback with linear disturbance rejection control is a common topic and many solutions were done. 4.      The paper needs a motivation (some gap in earlier designs or the assumptions that are not satisfied or something else). 5.      The paper appears technically correct however since it is basically a single point design of an observer-based feedback with linear controller that are not many new insights to be gained in the analysis.6.      The literature overview what is done in the manuscript does not look professional. Authors just say, paper by paper, what is done in every single manuscript. I recommend to Authors provide some expert view - analyse and compare the results in cited papers. 7.      Moreover, the literature review is lack of advanced method dealing with nonlinear observer-based for industrial applications i.e.

a.       A new scheme on robust observer-based control design for interconnected systems with application to an industrial utility boiler, IEEE Transactions on Control Systems TechnologyVolume 16, Issue 3, May 2008, Pages 539-547

b.      Experimental validation of the Newton observer for a nonlinear flux-controlled AMB system operated with zero-bias flux, International Journal of Control, DOI: 10.1080/00207179.2018.1552025, 2018.

a.       Sensorless small wind turbine with a sliding-mode observer for water heating applications, IECON 2015 - 41st Annual Conference of the IEEE Industrial Electronics Society

                          b.      Lyapunov sliding-mode observers with application for active magnetic bearing operated with zero–bias flux, Journal of Dynamic Systems Measurement and Control, Transactions of the ASME, DOI: 10.1115/1.4041978, Vol. 141, (2019). 8.      How the dynamic model and its parameters were derived for drum water level, there were obtained during identification? How this model is adequate? 9.      Why the extended state observer is applied to the linear stable model. 10.  What was the method for tuning the controller’s parameter? How the parameters were optimized?

11.  Fig.3, label “output (meter)” should be “water level [m]” ? 12.  Fig. 3, presents a high overshoot for LADRC, this needs comment. 13.  The experimental verification of proposed analytical designs and simulation outputs is welcome.

14.      All parameters and values of the water drum should be collected and given in Table.

15.      The controller effort (control signal) should be plotted and compared. The controller output energy that is putted to the system via control channel should be analysed.

16.      The conclusions should be supported with results. 
I invite Authors to respond to the reviewer comments and revise your paper.

Author Response

Thank you very much for your careful review and constructive suggestions with regard to our manuscript "Drum water level control based on improved  ADRC" (algorithms-524328).

Those comments are all valuable and very helpful for revising and improving our paper, as well as the importance guiding significance to our researches.

 We have studied these comments carefully and tried our best to revise and improve the manuscript.

The main corrections in the paper and the responds to your comments are as following:

Author Response File: Author Response.pdf

Reviewer 2 Report

The main purpose of this work is to design an improved active disturbance rejection control (IADRC) hybrid velocity and position controller for drum water level control. The main feature of this paper is adding an additional linear extended state observer to estimate the error of the linear observer for the total disturbance; therefore, the proposed control scheme not only ensure the control quality, but also simplify parameter tuning. The paper is well organized and technical sound.

Minor comments:

1.      For completeness, the proof of system robust stability should be included.

2.      There are many symbols and blocks in Figure 1 are not previously defined. Why Figure 1 is shown in different may with Figure 2?

Author Response

Thank you very much for your careful review and constructive suggestions with regard to our manuscript "Drum water level control based on improved ADRC  " (algorithms-524328).

Those comments are all valuable and very helpful for revising and improving our paper, as well as the importance guiding significance to our researches.

We have studied these comments carefully and tried our best to revise and improve the manuscript.

The main corrections in the paper and the responds to your comments are as following:

Author Response File: Author Response.pdf

Reviewer 3 Report

The idea of adding LESO2 is interesting.  However, the underlying theory is not articulate well.  Even with LESO2, there will still be estimation error.  Should we add LESO3?  And when to stop?

In line 70 to 71, it says "... the water level system can be simplified to a second-order system" but was not given explicitly.  Instead, Figure 1 was given without much explanation of the details, such as G_c1(s), G_w(s), etc., until subsection 3.1.  Even in subsection 3.1 there is no details of G_c1(s).  The reviewer guesses G_c1(s) is the sub-controller in the PID form with k_p = 1.2, k_i = 0.35 and k_d = 5.  Another question comes that if G_V(s) is constant (very fast dynamic compare to other part of the system), why a sub-controller is necessary?  And based on Figure 1 from U(s) to Y(s) is not a second order system any more.

In line 81, it reads "Therefore, the controller gain b_0_hat = b_0 is greater than zero.".  Is this an assumption of the paper or a conclusion?  If a conclusion, the reviewer does not see any reasoning here.

In line 110, it says "... by adding same observer before the existing LESO".  The reviewer believes that at least b_0_hat in (3) for LESO1 and LESO2 differs.

Also, the authors may want to explain in sub-section 3.1 (line 124 - 127) why b0 and omega_0 are different for LADRC and ILADRC, especially the big difference in omega_0 (1.12 compare to 40).  Is there a limitation in LADRC?

Author Response

Thank you very much for your careful review and constructive suggestions with regard to our manuscript "Drum water level control based on improved ADRC  " (algorithms-524328).

Your comments are all valuable and very helpful for us to improve the quality of our paper. We have studied these comments carefully and tried our best to revise the manuscript.

 The main corrections to the paper and the responds to your comments are as followings:

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Thank you for your improvments.

Reviewer 3 Report

The paper is improved by addressing comments from all reviewers.  This reviewer has no more comments.